Correct bugfix in Metadata-standard-names.md

[climbfuji]

Correct bugfix in Metadata-standard-names.md (replace _loop_extent with _dimension)

[gold2718]

Two comments:

1. This is not a bug, it happens when the host model metadata has horizontal_dimension but the scheme has horizontal_loop_extent (i.e., all the time for xx_run routines).
2. The markdown file is generated from the XML file, please edit the XML and follow the instructions in README.md to regenerate the markdown.

[climbfuji]

So shouldn't the host model provide both? Or are we ok with having only horizontal_dimension and use it for the _run routines when horizontal_loop_extend does not exist?

[gold2718]

The metadata for a host model field (say temperature) has one entry. That entry uses horizontal_dimension because that is the size of the data on the host model.
At run time, the host model will either pass the entire array, or will pass part of it in a loop (which may be threaded). In either case, the schemes interpret whatever the host model is sending as horizontal_loop_extent. That is why capgen can make that substitution during the analysis of xx_run scheme interfaces.

[climbfuji]

Got it, thanks for the explanation.